Sound recording and reproducing machine



Jan. 9, 1945. H. P. cLAusEN SOUND RECORDING AND REPRODUCING MACHINEv Filed Jan. 13, '1943 Patented Jan. 9, 1945 UNITED STATES PATENT oFFlcE i 'Y V2,366,956A l SOUND RECORDING AND `REPRODUCING 2 'MACHINE\ .Y Y Henry P. Clausen, White Plains, N. v4Y., assignor to ,i v Y The Gray` Manufacturing Companygrllartford,

, Conn., a corporation of Connecticut lApplication January k13,1943','SerlalvNm 472,185

" tion therefrom.

' ing and reproducting machine Hemploying a v`s claims.. `(ci. 17a-100.4)

- Vby gripping it between 'a power driven friction roller and an idler roller. By thus driving the record the spindle supporting it is caused Vto turn `This invention 'relates to improvements in sound recording and reproducing machines, such as so called dictation machines. 'I'he general lobject of thisi'invention to provide VaV greatly "simpliedvv mechanism` for purposes of sound recording Jon a kpermanent record and 'reproduc- In accordance with this Ygeneral object, a specific object of this'invention is to provide a practical machine of this type without the use of multistage vacuum tube amplifiers.

In accordance with this object, it is an objecty of this inventionto provide a dictation recordmechanical amplifier.

Another object of this invention is to provide a simplied form of `back spacing and forward spacing mechanism for machines of this type.

Another; object Vof the invention is to `provide means for indicating to the dictator that the 'i machine is in operation and ready to' receive dictation.

A stillzfurther object ofthe invention is to provide vcircuit control means'whereby, during reproduction, the :recording circuits, and particularly the microphonais disconnected so that no dis- Aturbing noises which might enterit can'l reach the reproducer.

Another object ofgthe invention is to provide a simplified means for preventing further operation of the machine when its record is full.

Additional andmore detailed objects of this invention will be apparent from Ythe following detailed description of one embodiment thereof.

\ This invention resides substantially in the combination, construction, arrangement and relative location of parts, all as will be described in detail below. f

'In the accompanying drawing, the single figure is a Vschematic and diagrammatic illustration of one form ofthe invention'. Y l, The mechanism illustratedin the drawing comprises a sound recording and reproducing machine of the type disclosedV in full detail in `United' States Patent ANo'. 2,296,870, issued September 29,1l42, .to B. A. Proctor et al. for Sound recording and reproducing in which ythe record comprises a thin flexible disc of suitable material, such as cellulose acetate. In this machine a'support is provided for the record which permits it to assume a curved form. 'Ihis record revolves on its center by reason of its keyed connection to a rotatable spindle which travels radially of the disc,` as it revolves. The power to operate it is applied directly to the record disc `and .it in turn drives mechanism which causes the spindle to have a transverse movement ina radial direction.

InI accordance with the; general object of simplication, the system herein disclosed does not use any formqof vacuum tube amplier. As is well known, amplifiers commonly used for this` purpose areY multi-stage and involve complexdelicate circuits with a multitude of resistors. in-

ductors and capacitors requiring accurate assembly and adjustment. In ,addition to being relatively bulky, vamplifiers of this type require j skilled maintenance which is an undesirable feature in many commercial installations.

i In accordance with this invention, amechanicalV ampliiier or,'as it is sometimes called, a mechanical repeater is employed for creating the necessary gain in the recording currents supplied by the microphone to the recording head.

6 Mechanical amplifiers orvrepeaters of this type are old andwell known in the electrical arts but it is believed that they have never been incorporated in a sound recording and dictation machine With the resultant simplification thereof. The core of thisinvention involves a Vnovel combination of such a mechanical ampliiler with a dictationrecordlng and reproducing machine `to provide a practical, efllcient operating assembly. It has been found that with suchamechanism, a gain of from 40 to 50 db. can be secured which isample for purposes of'a machine of this type.v

In addition, 'and in accordance with the general object of this invention, further simplifications have been effected to accomplish back spacing and forward spacing and other practical features,

as will be apparent from,V the following description. i y

Referring now to the illustration inthe drawing, the recording and reproducing machine itself is diagrammatically illustrated a's including a carriage I'which'is supported for rectilinear motion in anysuitable manner, as for example on rods, not'shown, as clearly illustrated in said patent. Journalled on the carriage I is a vertical spindle 2 which terminates at its upper end in a vseat for' 'the recording disc 1, which seat includes some formvof member for keying or locking the disc on the spindle. Qne suitable form o1' such mechanism is illustrated in the patent mentioned above. At this point, it may be noted that the subject matter of this invention is not limited to use with a flexible record disc but could be used with a rigid self-supporting recording disc as is now commonly used in the phonograph art. Secured to the spindle 2 is a worm 4 which meshes with a horizontal threaded shaft secured to the carriage I but capable of rotation on its axis. The threaded shaft 6 is engaged by a threaded half nut 6 which is flxed'so that as the shaft 6 Vrevolves it is caused to move axially in either direction depending upon its direction of rotation and, of course, to move the carriage I with it. In a commercial machine, the nut 6 is preferably pivotally mounted so that it can be disconnected from the shaft 5 returned to start a new record.

At 8 is illustrated a rotatable shaft upon which is secured a transversely extending arm 8 having cradles or forked ends in which the recording head III and the reproducing headII are mounted on trunnions so that they are suspended from the ends of the arm 8 as shown. At I2 is a motor driven friction wheel which engages the under surface of the record disc 1. Positioned above the wheel I2 is an idler wheel I3 adapted to engage the opposite side of the-disc 1 in diametrical relation to the wheel I2 so as to grip the disc between them. The idler wheel I3 is rotatably mounted on the end of a lever I4 which in turn is pivotally mounted at I6. Between its ends the lever is pivotally connected at I6 to the plunger I1 of a solenoid I8. The plunger projects below the solenoid so that when it descends it engages .the movable contact I9 of a switch which cooperates with a pair of fixed contacts as shown to'provide a single pole double throw switch. The contact I9 is connected to one terminal of a suitable current source 28, the other terminal of which is grounded. The uppermost contact of the pair of this switch is connected by a wire to any suitable form of current rectifier 2|, such as a copper oxide rectiner. The other Y terminal of this rectifier is connected to wire 43 and to one terminal of the secondary of a current supply transformer 22, the other terminal of which is grounded. The primary of this transformer is adapted to be connected to a suitable current source, such as the usual A. C. power and lighting circuit. The other terminal of this switch I8 is connected by a wire 23 to the fixed contact of switch 24.

Also secured to the shaft 3 is a pair of levers lying at an angle to each other to providev the forked member 25. At the outer ends of these levers are pivotally mounted pawls, as shown. These pawls cooperate, as will be described later -with the sets of ratchet teeth 6I and62 respectively formedon the carriage I. Projecting upwardly from `the shaft 8 is an arm 26 positioned to operate switch 24 and suitably shaped to provide an operating handle for the shaft 6 and its connected mechanism.

The movable contact of switch 24 is connected by wire 21 to the primaries of the repeating input transformer 484 and output transformer 28. The primary of transformer 28 isgprovi'ded in the form of two coils to one terminal of one of which the wire 21 is connected and the other terminal of which isconnected by a wire to one terminal of the microphone 23 forming part of the mechanical amplifier 30. One terminal of the other primary winding is grounded, as shown, and the other terminal is connected by wire 3I to the other terminal of the microphone 29. The secondary of transformer 28 has one terminal grounded and the other terminal connected byi wire 32 to one electrode of the neon lamp 34 when the carriage I is ohms. The other terminal of the receiver 36 is connected by wire 38 to the terminal of the microphone 38 which is grounded. Wire 38 is con- 'nected by wire 40 to one contact of a press switch 4I' forming partof the hand set. The other contact of this switch is connected by wire 42'to one terminal of the solenoid I8. The other terminal of the solenoid is connected to wire 43, previously mentioned, which wire extends to the fixed contact of a switch 44 which may be of the type knownl as a micro-switch requiring but little'movement to operate' it. This xed contact is mounted on a stop or a button, as illustrated in the drawing, so as to prevent further movement of the carriage I after the switch 44 is closed. The movable contact of switch 44 is connected by wire 45 to wire 46 which in turn connects wire v to one terminal of the reproducing head II, the other terminal of which is grounded. Here again, the reproducing head may be any one of the well known types in the f art as, for example, the electro-magnetic type or the piezo electric crystal type. The secondary of the repeating transformer 48 is connected to the winding 43 of the mechanical amplifier which is in cooperative' .relation with a permanently magnetized core 60.

Although mechanical amplifiers are well known in the art, it may be well to note that they comprise in the modern design a receiver and a microphone closely coupled. The diaphragm of the.

receiver comprises one contact of the microphone which is usually of the carbon granule type. It is also to be noted here that plunger I1 is in raised position, as shown, when solenoid I8 is de-energized and moves down when it is energized to cause the idler -roller I3 toV engage the record disc 1 under pressure. At this time, switch I8, which is normally in the position shown when solenoid I8 is de-energized, is moved downwardly to engage the-lower' fixed contact. As soon as solenoid I8 isde-energized, lever I4 raises and switch I8 moves back to normal position.

A descriptionof the operation of this system will now begin.

It will be assumed that the record`1, shown in the drawing, is a fresh record and that it has been impaled upon the spindle 2. in engagement withV the keying member 3 as shown. The half nut 6 is then 'raised and the carriage I is pushed to the extreme right since recording on this instrument begins near thel center of the record and proceeds in a spiral path to the edge thereof. In order to effectrecording, the dictator pushes the member 26 to the right causing clockwise 'rotation of shaft 8 whereupon the lever 9 underbe understood that the form of mechanism illustrated may not necessarily be the commercial form, as will be clear from the vabove mentioned patent, wherein the parts'are arranged so that the styli of the recorder and the reproducer may alternately be engaged with the record at apascenso Yproximately the samey radialdistance fromthe v audible signaly will be heard inthe'receiver 36;

center.' In order to start dictation, thev dictator picks up the -hand set 31 and presses switch 4I A. closed. Thev closingkof switch 54| completes a circuit vfrom thelground through wire 38,'wire 48,. switch, wire 42, solenoid;|8, wire 43to the 'secondary of 'transformer 22 and back toground. 'This energizessolenoid I8 whichpulls lever I4 The neon lamp 34 w i11 not be ,lightedV al1 the time down to cause the idler roller I3 to engage the record 1. Itwill beassumedthatthe motor driven pulley I2 isat this time in rotation.. There are many waysin which thercircuitfor the driving motor, Vnot shown, can be completed so that this will be true. Thegdownwardmovement of plunger I1Y also moves the Yblade of switch I9 into` engagement with the lower contact so 'that a 1 y circuit is completed `from the grounded -battery ysource 2l) through switch;l9, wire'23 switch 24, which `closed when the recording head III moved v linto engagementwith therecordrl, by wire 21 to the connected primaries of each ofthe trans- Y formers 48 and 28. .'Ifhe circuit Vfor the primaries.

of transformer 48 is completed togroundthrough the wire 41 and the microphone 39 and the circuit for the primaries of transformer 28 .is comthe end ofthe record has been reached. In the' pleted through the microphone' 9,V Wire'3l and connected primaryfto ground.

TheV gripping of the record ,Y 1.v between, the

-wheels'l2 .and I3 causes it to revolve at a predetermined rate.` of speed. Here itmay be Vnoted that in an actual machinetheaxes of rotation of the rollers I2 and I3 willbe'at rightangles to those shown in the gure as is Yclear from 'theV tration. As the disc 1 rotates, spindle 2 andworrn `4 will rotate with it'causingthe shaft 5 to reinchper revolution. s c Y In order to record the dictator speaks into ther microphone 39, the circuit ,iscompleted through the battery 20, as previously described, so that` thervarying sound .pressure waves. will cause ther` .microphone 39 to vchange` the resistance vinthis circuit in accordancewith the sounds rimpressed but will flash Vduring periods of soundnintensity high enough to causeespecially high current to iiow in the circuit 32-35. t this point it may be noted that' there are equivalent devices vwhich could be used in place of the lamp 34, such asa dryrectifler of the selenium or copper oxide type.

The dictatormayicontinue to record until the vend ofthe record, at vwhich time'the carriage VI will engage the micro-switch 44 Aand close it cornpleting a circuit from thel secondary of transformer 22 through switch 44, wire 45, wire 46 to ground through the receiver 36 and wire 38. Thealternating currentin the secondary of the transformer will impose acharacteristic tone current in this circuit apprising the vc'iictatorthat meantime thel movement'of the carriage will have been haltedby the stop` upon which the switch 44 ismounted.; Should the dictator continue to hold the switchv 4I closed, thez driving rolleIZ will merely slip on the record 1. Normally, however, when the dictator hears the characteristic tone in the receiver 36, he relieves pressure on switch 4I which opens breaking theclrcuit to solenoid I8 so that its plunger I1 rises and moves -above mentioned patent. Theyare shown in the f drawing out 0f normal position to facilitate illus-r the wheel I3 out of engagement withV the record .1 so that the recording machine stops. Switch I9 valso moves against a separatev contact connecting the battery 20 through the rectifier 2| so that during all off periods this battery will be re charged. The dictator then moves the shaft 8 back to neutralposition, as shown in the drawing. He may then removethe record 1 and replace it :with a fresh `one after which the above described operations may 'be completed.

Continuing this description of simple recording and reproduction, let it befassumed that a vfully recorded record 1 is placed on the machine.

The half nut Gis disengagedy andtheV carriage I is `moved'to the right so that reproduction can v be started from the centermost convolutions of the record. The operator 26 is then swung to the left causing counterclockwise rotation of shaft 8 andthe engagement lofthe stylus of reproducer .I with the record The dictator or transcriber Y may then press switch `4I again starting the rnathereon with the `result that currents correspondy Vphone 29. .Battery 20 is also in this vcircuit; so f that voice currents suitablyamplifled will be introduced into the secondary of transformer 28 which is included in ra circuit extending from ground through thesecondaryfwire 32,:wire 33, recording head I0 and ground. Thus-j the stylus of the recordinghead Ill will be vibrated to im'- press upon the-.record 1 a record which is -a physi'.-

cal reproduction of the sound waves strikingthe microphone 39. The currents flowing' through thewire 32 will also pass into the neon lamp 34, wire 35, receiver 36 ,and wire 38 to ground so that neon lamp 34 will flash as the dictator speaks signalling to him both visibly and audibly that the apparatus is in proper working condition. It

is, of course, apparent that the visible signal can fmitted through'lwire 46 tothe receiver 36.A

chine in operation, as previously described, so that the record will xbe reproduced by thepick up II andthe currents generated thereby transv will be noted, atY this time, that switchv 24 is be observedv by watching the lamp 34 and the 75 open so thatY the circuitlfrom the battery 20 to the primaries Vof the transformers 48 and 28 remains open. This is desirable so that Vno extraneousy noises entering the vmicrophone can be amplified and pass back tothe receiver 36 to interferewith the reproduction from the record. At thisetime, of course, the neon lamp 34 is not operating since the listener has the reproduction to tell him that the machine is in good operating condition. During recording or reproduction, release of switch 4I causes the machine to immediately stop, and upon pressing it to again start so that the dictator by thlssimple operation has Afull control-ofthe machine. Y lThe above description has been 'Without reierence to the back spacing mechanism which will now be described. YIf during dictation the dictator wishes to listen back to a previous portion of the recorded matter, he swings the operator 28 fromgrecordlng position to reproducing positionV and after thestylus of the reproducer II engages the record, he can, by additional movement of the operator 28, cause the pawl on the left hand arm of the fork 25 to engage one of the teeth l2 and move the carriage backward, that is to the right, one step for each such movement of the operator 26. The reproducing head Il is carried in the cradle in the end of the arm 9 so that after its stylus engages the record 'l further movement of the shaft 8 and hence the arm 9 has no effect on the reproducer since it is cradled on trunnions as shown. Repeated additional increments of back spacing movement can be given to the carriage and the record 1, as will be apparent, until the dictator has reached back into the recorded matter what hethinks is the proper distance.l He then starts the machine to reproduce that part of the record. If we assume that the dictator has listened to thepart he wishes and the record has not yet moved so that the stylus is at the end of the recorded matter, the dictator'may move the operator 26 to the right, disengaging the stylus of the reproducer Il from the record and engaging the stylus of the'recorder Il)y with the rec- Aord and then continuing the movement of the operator he can forward space the machine one step at a time for each additional step of the operator until the stylus of the recorder reaches the end f the' matter previously recorded, whereupon recording can go forward again as previously described. At the end of a piece of dictation, the dictator before beginning the next, can forward space the record one or 2 grooved distances to provide a visible indication as well as an audibleone during transcription to show the A, end of one piece of dictation and the beginning of another. It is apparent that by the incorporation in an obvious manner of a suitable detent, it will be possible t-apprize the operator of the machine by feel when. the operator 26 thas been moved far enough to engage either the reproducer or the recorder with the record SoV that he will `not continue the movement of the operator 26 to the point of causing either back spacing or forward spacing. In other words,

simply by feel hecan tell when Ythe heads are in accurate position without causing spacing movement when this is desired. Thus, the operator can engage or disengage either the recorder or the reproducerwith the record at'the same point when desired or at a point any desired number of A record grooves either side thereof on the same radius.

Fromrthe above description, it will be apparent to those skilled in the art that the subject matter oi this invention may =be embodied in other physical forms and it isfnot; desired, therefore, that the scope of protection afforded by the claims be limited solely by the disclosure but rather by a correct interpretation thereof in the ,light of the disclosure and the prior knowledge in the art.

What is claimed is:

1,"In a sound recording and reproducing machine, the combination comprising means for supporting and moving a record, a recording head, a reproducing'head, a microphone, a receiver, a mechanical amplifier, a circuit including said receiver and reproducing head, a circuit including said microphone, mechanical amplifier and recording head, whereby sounds may be ampliiied and recorded and reproduced, means for supporting the recording and reproducing heads adjacent the record, back spacing and forward spacing means and a single operator for causing alternative engagement of the reproducing and recording means with the record and forward spacing and back spacing respectively of the record.

2. In the combination of claim 1, volume indicating means connected to said receiver and means controlled by said operator for connecting said signalling means to the amplifier during recording.

3. In. a sound recording machine, the combination comprising means for rotatably` supporting a record, means 'for causing rotation of said record. a recording head, a microphone, an electro-mechanical amplifier, a current source, a circuit including saidV microphone, amplifier and recording head, a circuit including a switch for connecting said current source-to said amplifier, and means associated with said microphone for starting and stopping said means for rotating said record and for operating said switch during rotation ofvsaid record to complete said current source circuit.

4. In a sound recording machine, the combination comprising means for rotatably supporting a record, means for causing rotation of said record, a recording head, a microphone, a mechanical amplifler,` a current source, a circuit including said microphone. amplifier and recording head, a circuit including a switch 'for connecting said current source to said amplifier,

.- means for starting and stopping said means for rotating said record and for operating said switch during rotation of said record to complete said current source circuit and a rectifier connected by said switch to said current source when said record is standing still and disconnected from said current source when it is connected to said amplifier.

5. In a sound recording machine, the combination including means for supporting and moving a record, a recording head, a microphone, a mechanical amplifier, a circuit including the microphone, amplifier and recording head, whereby sound impressed uponv the microphone may be recorded on the record, a receiver, and means connected to said amplifier for indicating when the signal being recorded exceeds a desired volume 6. .In the combination of claim 5,v said indicating means comprising a gas discharge device. 7. In a sound recording machine, the combination including means for supporting and moving a record, a recording head, a microphone, a mechanical amplifier, a circuit including the microphone,y amplifier and recording head, whereby sound impressed upon the microphone may be recorded on the'record, a receiver, and meansconnected to said amplifier and to said receiver for indicating in said receiver when the signal -being recorded exceedsa desired volume.

8. In the combination of claim 7,'said indicating means comprising a gas discharge device.

HENRY P. CLAUSEN. 

